Single flavored kasutera, check! Double-flavored marbled kasutera, check! I did not make this one but it is out there. And now I present to you the triple-flavored Neapolitan Kasutera (Neapolitan Castella)! Achoo…talk about a persistent bug! This one shows no sign of abating. Have no fear though as this bug should not harm you unless you over-indulge. In fact, you may actually hope to catch it. 🙂
Neapolitan ice cream is a tri-colored combination of flavors, usually consisting of chocolate, vanilla, and strawberry ice cream in a single block. Adapting it to a cake baked in a single pan was quite a challenge but the result was pleasing to the eye and the taste combination delightful. The three separate flavors of different consistencies can be placed side by side into a single cake pan without them mixing together. Though not perfect, the tri-colored effect can definitely be achieved…YAY!

So, how did I prevent the three layers from mixing together? I used the Divider Method as described here. Making two flavors in a wide pan would be a lot easier. I wasn’t sure if three narrow strips would work as there was very little room for the batter to spread before it all got “messed” up. There was only one way to find out. I cut out two cardboard dividers and covered them with aluminum foil. Since I did not have a helper to hold up the dividers, I had to make sure they fitted snugly in the pan so that they could stand on their own.

After removing the dividers, the pan should be placed immediately into preheated oven. Needless to say I was frantic having to pause for pictures. As you can see, the different layers of batter were already starting to spread.

To make the three different flavors, I divided the base batter (after addition of mirin) into three equal portions of 4½oz (130g) each. Then I stirred in a little over a tablespoon cocoa mixture into one portion and honey mixture into another portion. The strawberry flavor was tricky. I felt that a tablespoon of strawberry would not be sufficient. Hence, I added all three tablespoons yielded from cooking down the sauce plus two drops of red food coloring to intensify the color. However, this meant that the strawberry batter would have a little more volume because of the additional liquid. Misjudging the appearance of the strawberry layer, I made the mistake of removing two tablespoons of the batter out of the pan resulting in the “wave” you see on the strawberry portion of the cake after baking. It was as if there was insufficient batter there. The top was smooth with very little to no shrinkage.

Apart from its wavy appearance, I must say this cake had the best flavor and texture compared to the Honey Kasutera and Matcha Kasutera I had made previously. The texture was very fine and a little more dense than the previous two cakes. This cake was moist and the mirin was definitely discernible. The strawberry flavor had a very mild tartness to it and combined well with the cocoa and honey flavors. I was more than happy.

For a kasutera that is even more Drop-Dead-Delicious, it must be given the customary “drop treatment”! I found this interesting study paper, Prevention of Shrinkage After Baking by H. Ohtsubo, T. Kanbe, Y. Kaneko, and S. Nomura explaining the physics of the “drop treatment”. In essence, baking causes expansion of cell walls in the cake until it hardens into rigid cells. As the cake cools, the pressure drops and no longer supports those walls causing shrinkage. A mechanical shock treatment applied to the cake immediately after baking cracks the cell walls relieving the pressure instantaneously to pre-empt the effects of shrinkage. Brilliant!

When dropping the cake, the traditional accompanying martial art’s cry kiai (気合) is highly optional but recommended as it may instantaneously release the pent up pressure within YOU! 😉

INGREDIENTS

Strawberry Sauce

5ozstrawberries(hulled and quartered) (150g)

1tspsugar

3tbspwater

2dropsred food coloring

INSTRUCTIONS

Line an 8¾in x 3¼in (22½cm x 8cm) loaf pan with aluminum foil. Cut two pieces of cardboard the width and height of the loaf pan to act as separators. Wrap cardboard separators with aluminum foil and place them equally spaced in the pan.

Place strawberries, sugar, and water in a small saucepan over medium heat. Mash strawberries with spatula and cook till thick and syrupy, about 8 minutes. Strain mixture, pressing with spatula to extract the juice. Discard pulp.

Stir cocoa powder with 1 tablespoon hot water in a small bowl till well combined. In another small bowl, combine honey with 1 tablespoon hot water.

Preheat oven to 325°F (165°C).

Place egg whites in mixing bowl and beat at high speed (speed 10*) for 30 seconds until slightly foamy. Add sugar in 2 to 3 increments until firm peaks form, about 4 minutes.

Add yolks one at a time at medium low speed (speed 4*) until well combined, about 1 minute. Add sifted bread flour and beat until just combined. Add mirin and continue to beat for another minute.

Pour batter through a sieve into a large bowl. Press with a spatula to help batter go through sieve.

Divide batter equally into 3 portions of 4½ oz (130g) each into 3 separate bowls. Add strawberry sauce (about 3 tablespoons) and 2 drops of red food coloring to one of the bowls and gently stir with a spatula till well combined. Repeat with cocoa mixture and honey mixture.

Pour each of the flavored batter into each section of the prepared loaf pan. Tap pan on the counter to remove air bubbles. Pull out both cardboard separators and immediately place into preheated oven.

Bake for 45 minutes or until top is evenly browned. Toothpick inserted into cake should come out clean.

Remove pan from oven and drop it from a one foot height onto the counter to prevent shrinkage. Place a piece of parchment paper on a large piece of shrink wrap. When cake is cool enough to handle, lift cake up by holding the edge of aluminum foil. Turn cake upside down onto parchment paper. Peel off aluminum foil. Wrap shrink wrap over cake and leave overnight in the refrigerator (right side up) to preserve moisture in the cake and for flavor to develop. Alternatively, warm cake can put into a Ziploc bag with the foil and left in the refrigerator (right side up) overnight.

To serve, cut off edges on all sides except the top and bottom with a very sharp knife. Then cut into thick slices using a sawing motion.

NUTRITION

Feedback from the field indicates that the previous two recipes were too sweet for some and too light for others. Can’t please everyone but glad to hear many LOVED it and have made it successfully! A few even made it repeatedly. 🙂 This Neapolitan Kasutera is the culmination of my three attempts and I think it has the best texture and flavor. I would highly recommend adding the mirin. It wasn’t in my Honey Castella because I was distracted with taking the step-by-step pictures and only realized the omission after the batter was in the pan. Below is the summary of my adjusted recipes for the different pan sizes. Use only one flavoring for each of the cakes. Please adjust the measurements of the flavorings accordingly if you intend to split the batter into two or three flavors.

The other two cakes… Please click on the picture to get to the post.

Finally, the key to a successful kasutera is patience. I know it is hard to refrain from eating the cake when it is fresh out of the oven but you will be glad you did. Wrap up the cake while still slightly warm and keep it in the refrigerator overnight. This finishing touch improves its moistness. Some have placed it upside down with no adverse effects while others placed it right side up in the fridge. I had the problem of the top of the cake sticking to the parchment paper and so I prefer to place it right side up with the parchment paper loosely covering the top.

I would like to mention here that my recipes are based on the original from

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Well done Biren! I hope to try making a castella cake soon, though I might be the only one eating it as hubs and my boys prefer rich moist cakes weeping butter or chocolate. Men! It’s beautiful, and the ‘wave’ though unintentional, is whimsical and quite pretty! When I do start making these sponge cakes, I will be referring to your site for guidance – thanks so much for taking the guesswork out of the process 🙂

Wow, this is going to be a tough act to follow!!! You know, I did say I will wait till you come for a visit before I ask you to make this? Well, I did pluck the courage to actually make your honey castella twice now, once with and once without the mirin. Both cakes came out so wonderfully well (though they did sag a bit) but they were both delicious! My daughter absolutely loved them and if she sees this neapolitan one, I will be in serious trouble! It would be fantastic if I can pull this off, but I am not holding my breath. I need a few more trial runs on tackling the sagging bit before I attempt this! Brilliant, Biren, as always!!!

Achoo indeed! I think I’ve caught the bug! The tri-color is gorgeous. Thanks for sharing the Divider Method and the summary (on excel?) is brilliant! I’m sure the cake tasted as good as they looked and how you spoilt your guys 🙂

Great cake! Very inventive recipe – congrats on this. Spectacular recipe. And really fascinating info about the drop treatment – I never knew. Now, thanks to you, I do! But I’m going to have to practice saying kiai! Thanks for a really fun post.

Your Neapolitan Kasutera looks wonderful! I know that castella cakes are relatively difficult to make; the fact that you have three flavors going on at once is just…wow!

I made my first attempt with your updated Honey Kasutera recipe (I appreciate the chart with the different sized pans–really helpful!). The flavor and texture was exactly as I had wanted, but just one thing: my cake rose a lot, and actually cracked on top upon 20-30 minutes or so of baking; I actually took it out after about 45 minutes and it was completely cooked through. I’ve noticed that most of my baked goods cook much faster than stated on recipes, so I’m guessing my oven is stronger than most ovens…anyway, would you recommend lowering the baking temperature, putting the rack up to the highest position, or just lessening the baking time?

Thanks Jackie for your compliments! I am glad to hear that your cake came out the way you wanted it in terms of flavor and texture. Glad to know too that the chart helped. 🙂

It sounds like your oven is a little stronger than most. Is it a convection oven? If so, you may want to try setting it to 300°F or 150°C. Cracking is usually caused by the cake rising too quickly in an oven that is too hot. I would just reduce the heat alone for now (i.e. change one unknown at a time) and see what happens. Unfortunately, it could take a few trials before you get it just right. Alternatively, you may want to invest in an oven thermometer to take the guess work out of the equation, especially if you do a lot of baking.

Thanks for the tip Biren! My oven is conventional, but for some reason, it tends to bake things really quickly; I often have to take food out much earlier than the stated baking time to prevent burning. I’ll try baking the cake at 300 degrees F next time and see how it goes. I’ll definitely be making this again; I sliced the cake yesterday morning and it was completely gone by this morning! Thanks again. 🙂

I tried making this cake today because of your lovely pictures and ideas:) I decided on Matcha/Chocolate/Strawberry. I mixed 2T matcha, 2T chocolate into 2T hot water, the paste was quite thick (I did not add more hot water to the paste because I was afraid to add too much liquid to the batter), therefore it was really hard to mix the paste into the batter smoothly. I ended up with small little clumps of matcha and chocolate in the batter. Did I do something wrong? The strawberry mixed in perfectly because it was more liquid.

My batter before mixing in the different flavors was quite fluffy and thick, is this correct or should it have been more liquid and soft? Sorry for so many questions, thank you for your help. My husband and I really enjoyed the taste of this cake, just wanted the cake to be prettier so I can make it for my MOM for mother’s day!

Firstly, thank you for your compliments. I am glad to hear that you and your husband enjoyed the cake. 🙂

The batter should be thick and fluffy to give the cake a nice even texture. How many eggs did you use for the batter? As for the flavoring, I would use one tablespoon each of matcha and cocoa mixed with one tablespoon of water. The measurements given are for a whole cake with just one flavor. Make sure the matcha and cocoa are properly dissolved in the hot water. Yes, it will be quite thick. Mix into the batter gently but thoroughly.

If you are making just one flavor, as per my notes, sift the matcha or cocoa with the flour to get it evenly and thoroughly mixed. Please refer to my Matcha Kasutera post for the method.

Oh wow. What a lovely blog you have – so pleased to have found your website. Thank you for sharing your lovely recipe and wonderfully detailed tutorial. I love baking but lack confidence, you have inspired me however. So much thought, time, effort and love has gone into your recipe and I think it is wonderful that you have taken the time to repond to the comments and questions posted above. Thank you for this unusual recipe. A very hard act to follow, I thought the wave was deliberate, and actually really like it 🙂